Since 1981 15 cases of renal disease have been identified in children infected with the Human Immunodeficiency Virus (HIV) in Miami. This number represents approximately 8% of the total population of children with HIV infection that is currently being followed at the University of Miami. Most of these children initially presented with proteinuria and nephrosis. Histologically these cases are associated with a diverse array of findings including focal segmental sclerosis (FSS), diffuse or focal mesangial hyperplasia (MH), minimal change (MC), SLE-like changes ("SLE") and tubulo-interstitial nephropathy (TIN). We propose to begin a prospective case controlled study of the HIV-associated nephropathy in children perinatally infected with HIV. All infants born at the University of Miami/Jackson Memorial Medical Center (UM/JMH) and who are HIV-infected will be included in the study and prospectively followed from the day of birth to document development of the nephropathy. It will be required that infants be born at UM/JMH and that they have no other type of gross birth defect identified. Each infant enrolled will be seen every three months and have a urine Labstix (registered trademark) for screening; those with abnormal findings will be studied (as indicated) by urinalysis, CBC, serum electrolytes and creatinine, renal ultrasound, urine culture, renal scan, voiding cystourethrogram, renal tubular function evaluation, degree of proteinuria, serological tests, glomerular filtration rate, effective renal blood flow, and filtration fraction. Those patients with persistent abnormal proteinuria or hematuria, increased kidney size or echogenicity, or decreased GFR will have a Gallium scan and a renal biopsy. An attempt will be made to elucidate the pathogenesis of the HIV associated nephropathy by performing antigen-antibody elution experiments, using molecular probes to detect viral protein expression in renal parenchyma, and assessing tissue infiltrating lymphocytes, inflammatory cells, HIV receptors, and ultrastructural markers. An effort will also be made to identify certain clinical indicators which can predict the development of, or correlate with the severity of, the renal disease.